1. Field of the Invention
The invention relates to a power supply system and, more particularly, to a power supply system which can switch the power supply path of a central processing unit (CPU).
2. Description of the Related Art
With the development of science and technology, the central processing unit (CPU) of new generation does not emphasize on working frequency but on saving power and high efficiency. Therefore, CPU manufactures develop dual core processors to replace conventional single core processors. Meanwhile, multiple CPUs are also applied in personal computers.
Generally speaking, each CPU has a corresponding voltage regulator module (VRM) to supply power, wherein the VRM often includes a reference voltage generator (DAC), a pulse width controller, a core voltage driver, and so on. Moreover, the VRM is often disposed on the motherboard, and the VRM of a specific type can only be used with its corresponding CPU. For example, the VRM conforming to power standard of VRM 10.1 and the VRM conforming to power standard of VRM 11 can not be used to any CPU at will.
FIG. 1 is a diagram showing a conventional power supply for multiple CPUs. In FIG. 1, the power of the CPU 101 is supplied by the VRM 102, and the power of the CPU 103 is supplied by the VRM 104.
However, with the development of speed and functions of the CPU, the power needed by the CPU is also increasing, and when upgrading the CPU, the original power of the VRM may be inadequate. This results in the fact that consumers are forced to replace the motherboard when upgrading the CPU because the voltage regulator module (VRM) cannot supply adequate power.
For example, the maximum rated power needed by the CPUs 101 and 103 in FIG. 1 is 60 W respectively, and the VRMs 102 and 104 also can provide 60 W respectively. When upgrading the CPU 101 or the CPU 103, if the maximum rated power needed by the upgraded CPU is 80 W, then neither the VRM 102 nor the VRM 104 can provide the power, it is obvious that they are not adequate, at this time the consumer has to change the motherboard to upgrade the CPU. This doesn't conform to economic benefits, and further results in waste.